Sophie asks Kevin how Miguel is. It is later revealed that Kevin and Sophie separated at the same time that Miguel and Rebecca lost touch for a bit. She did not keep up with the family so there would not be any way for her to know that Miguel was still in Kevin's life and had been married to Rebecca.
When Rebecca and Jack get married Miguel gives a speech which makes it seem that he and Jack had been friends for years and that it predated Jack knowing Rebecca. Subsequent episodes would show that Jack and Miguel met when Jack went into a store to buy a sport coat for for.a date with Rebecca several weeks into their relationship.
The train that Kevin and Sophie get on is supposed to be the New York City subway but looks nothing like it. The seats are more like the DC Metro. In NYC they have no fabric anywhere.